Taiji quan – also written alternately as taijiquan, t'ai chi and tai chi chuan – is an "internal" (wudang) Chinese martial art (in contrast to the "external" (shaolin) Chinese martial arts.
Some practitioners of wushu, especially those with an interest in China's earlier, homegrown religion, Taoism (Taoism, alternatively, Daoism, was as much a philosophy as a belief system), likened the distinction between the internal versus the external forms of wushu to the distinction between the yin ("dark", "cold") and the yang ("bright", "hot – though the yin and the yang could represent any particular set of seemingly opposing concepts such as good verses evil, male versus female, etc., the point being that the two were in fact intimately intertwined, or 'two sides of the same coin', as is suggested by the yin and yang symbol itself).
Taiji quan, according to one legend, was developed by a Taoist immortal (the Buddhist equivalent would be one who has achieved nirvanna) by the name of Chang San-feng (alternatively, Zhang Sanfeng ) who was inspired to develop this internal wushu discipline while witnessing a duel between a cobra and an eagle. Chang San-feng was impressed by the defensive tactics deployed by the snake (had the cobra attempted to flee it would have been paralyzingly wounded by the eagle's piercing peck, then strangled to death in the clutch of the eagle's powerful claws). By controlling its fear and maintaining total concentration on the eagle's various lunges and retreats, the cobra managed not only to avoid being hit by the eagle's deadly pecks, but itself managed to deliver a fatal blow to the eagle's neck, killing it.
Other theories concerning the origin of taiji quan hold that the discipline was developed over many centuries as a result of the painstaking work of many different kung fu ("hard-won achievement") masters, and as such represents a genuine synthesis of both the internal as well as the external form of kung fu wushu. Whichever explanation is the most likely (others may yet appear), the fact remains that although taiji quan, according to what is known of it via the historical record, first began to be formulated near the end of the 17th century, while it was first introduced as a complete, ready to be practiced discipline at the beginning of the 20th century.
There are five traditional schools of taiji quan: Chen, Yang, Wu/Hao, Wu and Sun. the sport is growing in popularity, as much for the secondary health benefits it confers as much as for the sense of self-confidence it engenders. Clinical studies suggest that the practice of taiji quan can lower blood pressure, reduce nervous tension, and benefit the immune system as well as improve the functioning of the digestive, cardiovascular and respiratory systems.
Today, there are over 100 million happy devotees who practice taiji quan on a regular basis.